A
program chart gives an attractive graphical presentation of
courses
in a program (or set of related programs), organized by terms or years, linked by
pre- and co-requisite arrows, and, when possible, supplemented by timetable information.
They are sometimes termed prerequisite charts or prerequisite diagrams,
especially when timetable information is not provided.

Who would use a program chart?

Program charts are useful to students selecting courses and planning their
programs, and to faculty and staff advising students and managing curriculum
development.

The information is already available in calendars and on-line. Why is a program chart needed?

Conventional sources of course, program and timetable information
are rarely in
a user-friendly format.
Faculty and staff advisors, being already fairly familiar with their courses and
programs,
often do not appreciate how inconvenient it is for students to access all the information
they need to make course choices.

For example, program requirements are typically specified as lists
of course codes for required and optional courses; one must look elsewhere to find the
titles of the courses,
the relations between them, their prerequisites, and the timetabling information.

As another example, a course description in a calendar typically specifies what the prerequisite courses
are, but hardly ever specifies which course or courses the course is prerequisite to.
This information may be very important to a student, but to
discover it, he or she must search through all
the subsequent course descriptions in the calendar. With a program chart, it is
evident at a glance.

As a third example, consider a student who wants to know whether they
can defer a course till the following year without risk of timetable
conflicts. With conventional sources of information, such a question can be
answered only by
doing an exhaustive search through both
timetable and calendar for a possible conflict. A program chart incorporating timetable
data provides the
necessary information in a compact and usable form, and the question can
be answered immediately.

If program charts are so great, why doesn't every university
department have them?

Few academic departments have the resources to produce
program charts.
If one Googles for "prerequisite diagram" or "prerequisite chart," there are many
matches; here are some of these:

Virtually all of the charts on the web are from
departments that
one would expect to have expertise in technical drawings.

Where can I see
PREREX
charts in use?

There are charts for both specialized and multi-disciplinary
programs on-line
here.

What file formats are used for
PREREX
charts?

The charts themselves are normally distributed in the Portable Document
Format (PDF) defined by Adobe; PDFs are readable on any platform and
in most browsers using freely-available software (such
as the
Adobe Reader), printable on any
high-resolution printer, relatively compact, and scalable to accommodate
paper size, display resolution, or user preference.

On request,
we will also deliver charts in Portable Network Graphics (PNG) format
for in-line use on a web page. PNG format is also relatively compact and
can be rendered directly by most web browsers. Other formats such as SVG (scalable vector graphics)
are possible.

PREREX
charts are produced by software that processes simple and convenient text-based descriptions.
When a
PREREX
chart is commissioned, the
chart description and the key software needed to do the processing are delivered
with the chart to
allow modifications
and updates. This is explained further in the following.

Who owns PREREX-produced program charts?

If you commission PREREX
to implement a chart, the chart and the chart description used to produce it belong to you; you decide how, where, and to whom to
distribute it.

How can
PREREX
charts be modified?

University programs and timetables evolve: courses are added or dropped, pre- or co-requisites
or timetabling of courses
change, and so on. A department will want to keep a program chart
up to date, without feeling locked-in to a single source of support.
The technology underlying
PREREX
charts makes it possible for
university faculty or
staff to make minor changes by editing
and
re-processing the chart description. On a moderately fast computer,
processing is virtually instantaneous, so it is practical to monitor
the state of a chart after every change to the description.

All
of the software necessary to process, preview, print out, and convert
PREREX
charts is open-source and legally downloadable from
web repositories (or, if desired, available from commercial suppliers), runs on all
platforms, and is easily installed.
Complete details are given in the
Maintenance Manual for
Program Charts.

Use of a separate text-based description file
and intelligent processing software make it easy
to modify a
PREREX
chart. If the text within a course box is changed,
the size of the box, the length of connectors to and from that box, and
the location of arrowheads into the box are all adjusted automatically by
the processing software.
If a course box must be moved,
it is straightforward to edit the
relevant instructions for arrows into or from the box because the coordinates specified for an arrow
are those of the box centres, rather than those of the
edges or corners of the boxes.
Small changes can be made with any text editor, such as Notepad.
For more substantial changes,
an interactive chart editor is available; it supports add, remove,
cut-and-paste, and edit operations on diagram elements, and shifts of
an entire diagram. The effects of these operations may be observed,
after saving and re-processing, in a PDF viewer, without exiting the
editor.
Editing a text file in either of these ways
is far easier and faster than trying to fiddle with an image using
a mouse.

If a client is unwilling to maintain their charts themselves, we
provide an optional support service.

What software is used to produce PREREX program charts?

To process the description of a PREREX
chart, the following software is essential:

an up-to-date standard-conforming implementation of LaTeX, such as the "basic"
MikTex distribution for Windows systems;

a file prerex.sty of specialized LaTeX definitions;

a few additional LaTeX packages, such as pstricks.

All of these items are readily available in web repositories
around the world and easily installed. For example, the MikTeX package manager will
actually download and install all needed standard packages automatically the first time a
chart is processed.

suitable fonts, such as the URW-Classico implementations of Optima and LaTeX support
files available
here (files uop.txt and uop.zip).

the prerex interactive editor for
PREREX
charts; this can easily be compiled for use on any Unix-like platform, such
as Linux, Solaris, Cygwin on Windows, Fink on OS X, and so on.

Why couldn't I use a program like Visio® or CorelDRAW® to produce a program chart?

You could, if you have such a program available, are very skilled in its use,
have the time to produce the desired chart,
and won't be embarrassed distributing a chart that looks amateurish.
Look carefully at a
PREREX
chart and notice the following properties:

Each course box is sized to just enclose the text within it,
with uniform standard margins.

Each arrow between courses is oriented from box centre to box centre,
rather than from/to standard "connection points" on the box edges.

The arrows are "clipped" by the course boxes, but the arrow heads
abut the target box exactly.

These desirable properties are not easily achieved using conventional
"do-it-yourself" drawing software, no matter how "user-friendly"
it purports to be.

The
technology we use provides
complete flexibility as well as professional quality:

Text within a course box may be partitioned into regions with varying
characteristics. For example, the course
code and the timetable information on the first line of course boxes are in a smaller font
than the course name. The latter is centered and the former are left- and
right-justified, respectively.

Any available Type 1 (Postscript) or TrueType format fonts may be used;
in the charts linked to above, the typeface used is FrutigerNext, a very legible sans serif
face. The professional-quality typesetting
engine takes advantage of kerns and ligatures in the fonts.

Line thickness
for boxes may be varied; in the example diagram, heavier boxes
(and bold-face text) are used to indicate
that a course is "required" in the program, rather than an option.

Different styles of connectors
can be used, for example to distinguish pre-requisites, co-requisites, and recommended
pre-requisites.

Various sizes or shapes of course boxes may be used, for example
to distinguish between half and full courses.

Graphic images such as logos can be imported.

Colours and hyperlinks to on-line course descriptions or calendars
are possible.

Wouldn't a commercial drafting service be able to produce a professional-quality
program chart?

Possibly, but you will almost certainly have to do the global lay-out yourself.
A more serious long-term problem is that it
is unlikely
you will be able to maintain the chart yourself using freely available software.
You will be "locked-in" to use the drafting service for every future modification
of the chart.

How much does a
PREREX
chart cost?

Our rate for producing or editing charts is $100 per hour.
Each chart is unique, but production of a chart "from scatch" typically requires two to three hours.

What does one get with a
PREREX
chart?

A chart package as delivered consists of the following files in a zipped archive:

the chart itself, in PDF;

the chart in PNG format (if requested);

the source file describing the chart, to allow editing and updating;

a file prerex.sty of LaTeX definitions supporting the production of
PREREX
charts;

a chart "maintenance manual," which has detailed instructions on how to install
and use the software necessary to edit and process the source file in order to
produce updated or modified charts.